CN110780204A - SOC estimation method for battery pack of electric vehicle - Google Patents
SOC estimation method for battery pack of electric vehicle Download PDFInfo
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- CN110780204A CN110780204A CN201911094161.0A CN201911094161A CN110780204A CN 110780204 A CN110780204 A CN 110780204A CN 201911094161 A CN201911094161 A CN 201911094161A CN 110780204 A CN110780204 A CN 110780204A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/385—Arrangements for measuring battery or accumulator variables
- G01R31/387—Determining ampere-hour charge capacity or SoC
- G01R31/388—Determining ampere-hour charge capacity or SoC involving voltage measurements
Abstract
The invention discloses an SOC estimation method of an electric vehicle battery pack, which comprises the following estimation algorithm flows: A. in order to meet the requirements of an electric automobile energy management system on offline and online estimation of the battery state, the accuracy and complexity of a model are comprehensively considered, a first-order RC equivalent circuit is selected for modeling the battery pack, and the voltage and current values of the actual battery pack are collected; B. and under a Matlab/Simscape platform, establishing a battery cell average model based on a first-order RC equivalent circuit model. According to the invention, through the flow matching of the step A, the step B, the step C, the step D and the step E, the accurate estimated values of the voltage and the capacity of the battery pack can be obtained under the operations of a least square method, DV and IC curve characteristic points and an ampere-hour integration method for the voltage and the capacity of the battery pack, the problem that the SOC value precision of the battery pack is reduced by a traditional estimation method is solved, a user can accurately monitor the power supply capacity of the battery pack according to the SOC value of the battery pack, and the brand influence and the purchasing power of the electric automobile are improved.
Description
Technical Field
The invention relates to the technical field of electric automobiles, in particular to a method for estimating the SOC of a battery pack of an electric automobile.
Background
The electric automobile is a vehicle which takes a vehicle-mounted power supply as power and drives wheels by a motor, meets various requirements of road traffic and safety regulations, and has the working principle that: accumulator-current-power regulator-motor-power transmission system-driving automobile.
The battery pack is used as a driving power source of the electric automobile, when the battery pack is manufactured, the SOC of the battery pack needs to be estimated due to the characteristics of the battery pack, however, the traditional estimation method has 5% -15% of uncertainty in the calculation process of the SOC value of the battery pack, the precision of the SOC value of the battery pack is greatly reduced, the accurate detection of a user on the voltage and the capacity of the battery pack is reduced, the cruising range and the power output of the electric automobile are directly influenced, and the brand influence and the purchasing power of the electric automobile are reduced.
Disclosure of Invention
The invention aims to provide an SOC estimation method of a battery pack of an electric vehicle, which has the advantage of estimation accuracy and solves the problem that the traditional estimation method reduces the accuracy of the SOC value of the battery pack.
In order to achieve the purpose, the invention provides the following technical scheme: an estimation method for the SOC of an electric vehicle battery pack comprises the following steps:
A. a first-order RC equivalent circuit is selected to model the battery pack, and the voltage and current values of the actual battery pack are collected;
B. establishing a battery average model of the battery pack based on a first-order RC equivalent circuit model, performing a mixed pulse power performance test, extracting battery model parameters by adopting a least square method, and drawing the model parameters into DV and IC curves;
C. detecting whether the actual voltage and current values of the battery pack reach the characteristic points or not, and if so, solving the capacity of the battery pack according to the relation between the characteristic points and the battery capacity;
D. if the actual voltage and current values of the battery pack do not reach the characteristic points, further detecting whether a charge-discharge cut-off condition is reached, and if the charge-discharge cut-off condition is reached, performing cluster analysis on the voltage curve of the battery pack;
E. then, a least square method is used for solving the curve transformation coefficient, the battery pack capacity is solved according to the relation between the transformation coefficient and the battery pack capacity, and then the estimated value of the battery pack is obtained based on the DV and IC curve characteristics calibrated offline and the relation between the transformation coefficient and the battery pack capacity.
The method for estimating the SOC of the battery pack of the electric vehicle as described above, wherein, optionally, the first-order RC equivalent circuit model in step B includes a temperature calculation submodel, an SOC submodel, an open-circuit voltage description submodel, an ohmic internal resistance description submodel, a polarization internal resistance and a polarization capacitance description submodel.
The method for estimating the SOC of the battery pack of the electric vehicle as described above, wherein optionally, in step B, the battery pack average model is corrected through Kalman filtering and is estimated based on an ampere-hour integration method.
The method for estimating the SOC of the battery pack of the electric vehicle as described above, optionally, further includes obtaining a time delay through a correction operation, and using the time delay as an input parameter of the ampere-hour integration method.
The method for estimating SOC of battery pack of electric vehicle as described above, wherein, optionally, the characteristic points in step C are based on principle of ICA and DVA method, and the correlation between the battery pack capacity and DV and IC curves is analyzed, and the battery pack state of health is characterized by using characteristic values and transformation coefficients of DV and IC curves of the battery pack.
The method for estimating the SOC of the battery pack of the electric vehicle as described above, wherein step B is optionally performed under a Matlab/simscape platform.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, through the flow matching of the step A, the step B, the step C, the step D and the step E, the accurate estimated values of the voltage and the capacity of the battery pack can be obtained under the operations of a least square method, DV and IC curve characteristic points and an ampere-hour integral method on the voltage and the capacity of the battery pack, the problem that the SOC value accuracy of the battery pack is reduced by a traditional estimation method is solved, a user can conveniently and accurately monitor the power supply capacity of the battery pack according to the SOC value of the battery pack, the endurance mileage and the power output of an electric automobile are prolonged, and the brand influence and the purchasing power of the electric automobile are improved.
Drawings
FIG. 1 is a flow chart of a battery capacity estimation algorithm of the present invention;
fig. 2 is a flow chart of a battery pack algorithm according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-2, an estimation method of the SOC of the battery pack of the electric vehicle includes the following steps:
A. in order to meet the requirements of an electric automobile energy management system on offline and online estimation of the battery state, the accuracy and complexity of a model are comprehensively considered, a first-order RC equivalent circuit is selected for modeling the battery pack, and the voltage and current values of the actual battery pack are collected;
B. under a Matlab/Simscape platform, establishing a battery cell average model based on a first-order RC equivalent circuit model, performing a mixed pulse power performance test, extracting battery model parameters by adopting a least square method, and drawing the model parameters into DV and IC curves;
C. detecting whether the actual voltage and current values of the battery pack reach the characteristic points or not, and if so, solving the capacity of the battery pack according to the relation between the characteristic points and the battery capacity;
D. if the actual voltage and current values of the battery pack do not reach the characteristic points, further detecting whether a charge-discharge cut-off condition is reached, and if the charge-discharge cut-off condition is reached, performing cluster analysis on the voltage curve of the battery pack;
E. then, a least square method is used for solving the curve transformation coefficient, the battery pack capacity is solved according to the relation between the transformation coefficient and the battery pack capacity, and then the estimated value of the battery pack is obtained based on the DV and IC curve characteristics calibrated offline and the relation between the transformation coefficient and the battery pack capacity.
The first embodiment is as follows:
an estimation method for the SOC of an electric vehicle battery pack comprises the following estimation algorithm flows:
A. in order to meet the requirements of an electric automobile energy management system on offline and online estimation of the battery state, the accuracy and complexity of a model are comprehensively considered, a first-order RC equivalent circuit is selected for modeling the battery pack, and the voltage and current values of the actual battery pack are collected;
B. under a Matlab/Simscape platform, establishing a battery cell average model based on a first-order RC equivalent circuit model, performing a mixed pulse power performance test, extracting battery model parameters by adopting a least square method, and drawing the model parameters into DV and IC curves;
C. detecting whether the actual voltage and current values of the battery pack reach the characteristic points or not, and if so, solving the capacity of the battery pack according to the relation between the characteristic points and the battery capacity;
D. if the actual voltage and current values of the battery pack do not reach the characteristic points, further detecting whether a charge-discharge cut-off condition is reached, and if the charge-discharge cut-off condition is reached, performing cluster analysis on the voltage curve of the battery pack;
E. then, a least square method is used for solving the curve transformation coefficient, the battery pack capacity is solved according to the relation between the transformation coefficient and the battery pack capacity, and then the estimated value of the battery pack is obtained based on the DV and IC curve characteristics calibrated offline and the relation between the transformation coefficient and the battery pack capacity.
Example two:
in example one, the following additional steps were added:
and in the step B, the first-order RC equivalent circuit model comprises a temperature calculation submodel, an SOC submodel, an open-circuit voltage description submodel, an ohm internal resistance description submodel and a polarization internal resistance and polarization capacitance description submodel.
An estimation method for the SOC of an electric vehicle battery pack comprises the following estimation algorithm flows:
A. in order to meet the requirements of an electric automobile energy management system on offline and online estimation of the battery state, the accuracy and complexity of a model are comprehensively considered, a first-order RC equivalent circuit is selected for modeling the battery pack, and the voltage and current values of the actual battery pack are collected;
B. under a Matlab/Simscape platform, establishing a battery cell average model based on a first-order RC equivalent circuit model, performing a mixed pulse power performance test, extracting battery model parameters by adopting a least square method, and drawing the model parameters into DV and IC curves;
C. detecting whether the actual voltage and current values of the battery pack reach the characteristic points or not, and if so, solving the capacity of the battery pack according to the relation between the characteristic points and the battery capacity;
D. if the actual voltage and current values of the battery pack do not reach the characteristic points, further detecting whether a charge-discharge cut-off condition is reached, and if the charge-discharge cut-off condition is reached, performing cluster analysis on the voltage curve of the battery pack;
E. then, a least square method is used for solving the curve transformation coefficient, the battery pack capacity is solved according to the relation between the transformation coefficient and the battery pack capacity, and then the estimated value of the battery pack is obtained based on the DV and IC curve characteristics calibrated offline and the relation between the transformation coefficient and the battery pack capacity.
Example three:
in example two, the following additional steps were added:
in the step B, the battery cell average model is corrected through Kalman filtering and is calculated and estimated based on an ampere-hour integration method, and the specific estimation method flow is shown in fig. 2. Specifically, the time delay is obtained through correction operation and is used as an input parameter of an ampere-hour integration method, so that the used time of integration is more accurate, the result of installing the integration is more accurate, and the real-time adjustment of the deviation generated in the calculation process is facilitated.
An estimation method for the SOC of an electric vehicle battery pack comprises the following estimation algorithm flows:
A. in order to meet the requirements of an electric automobile energy management system on offline and online estimation of the battery state, the accuracy and complexity of a model are comprehensively considered, a first-order RC equivalent circuit is selected for modeling the battery pack, and the voltage and current values of the actual battery pack are collected;
B. under a Matlab/Simscape platform, establishing a battery cell average model based on a first-order RC equivalent circuit model, performing a mixed pulse power performance test, extracting battery model parameters by adopting a least square method, and drawing the model parameters into DV and IC curves;
C. detecting whether the actual voltage and current values of the battery pack reach the characteristic points or not, and if so, solving the capacity of the battery pack according to the relation between the characteristic points and the battery capacity;
D. if the actual voltage and current values of the battery pack do not reach the characteristic points, further detecting whether a charge-discharge cut-off condition is reached, and if the charge-discharge cut-off condition is reached, performing cluster analysis on the voltage curve of the battery pack;
E. then, a least square method is used for solving the curve transformation coefficient, the battery pack capacity is solved according to the relation between the transformation coefficient and the battery pack capacity, and then the estimated value of the battery pack is obtained based on the DV and IC curve characteristics calibrated offline and the relation between the transformation coefficient and the battery pack capacity.
Example four:
in example three, the following additional steps were added:
and C, analyzing the relevance of the battery pack capacity and DV and IC curves by referring to the principle of ICA and DVA methods and using characteristic values and transformation coefficients of the DV and IC curves of the battery pack to represent the health of the battery pack.
An estimation method for the SOC of an electric vehicle battery pack comprises the following estimation algorithm flows:
A. in order to meet the requirements of an electric automobile energy management system on offline and online estimation of the battery state, the accuracy and complexity of a model are comprehensively considered, a first-order RC equivalent circuit is selected for modeling the battery pack, and the voltage and current values of the actual battery pack are collected;
B. under a Matlab/Simscape platform, establishing a battery cell average model based on a first-order RC equivalent circuit model, performing a mixed pulse power performance test, extracting battery model parameters by adopting a least square method, and drawing the model parameters into DV and IC curves;
C. detecting whether the actual voltage and current values of the battery pack reach the characteristic points or not, and if so, solving the capacity of the battery pack according to the relation between the characteristic points and the battery capacity;
D. if the actual voltage and current values of the battery pack do not reach the characteristic points, further detecting whether a charge-discharge cut-off condition is reached, and if the charge-discharge cut-off condition is reached, performing cluster analysis on the voltage curve of the battery pack;
E. then, a least square method is used for solving the curve transformation coefficient, the battery pack capacity is solved according to the relation between the transformation coefficient and the battery pack capacity, and then the estimated value of the battery pack is obtained based on the DV and IC curve characteristics calibrated offline and the relation between the transformation coefficient and the battery pack capacity.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (6)
1. A method for estimating the SOC of a battery pack of an electric vehicle is characterized in that: the estimation algorithm flow is as follows:
A. a first-order RC equivalent circuit is selected to model the battery pack, and the voltage and current values of the actual battery pack are collected;
B. establishing a battery average model of the battery pack based on a first-order RC equivalent circuit model, performing a mixed pulse power performance test, extracting battery model parameters by adopting a least square method, and drawing the model parameters into DV and IC curves;
C. detecting whether the actual voltage and current values of the battery pack reach the characteristic points or not, and if so, solving the capacity of the battery pack according to the relation between the characteristic points and the battery capacity;
D. if the actual voltage and current values of the battery pack do not reach the characteristic points, further detecting whether a charge-discharge cut-off condition is reached, and if the charge-discharge cut-off condition is reached, performing cluster analysis on the voltage curve of the battery pack;
E. then, a least square method is used for solving the curve transformation coefficient, the battery pack capacity is solved according to the relation between the transformation coefficient and the battery pack capacity, and then the estimated value of the battery pack is obtained based on the DV and IC curve characteristics calibrated offline and the relation between the transformation coefficient and the battery pack capacity.
2. The method for estimating the SOC of the battery pack of the electric vehicle according to claim 1, wherein: and the first-order RC equivalent circuit model in the step B comprises a temperature calculation submodel, an SOC submodel, an open-circuit voltage description submodel, an ohm internal resistance description submodel, a polarization internal resistance and polarization capacitance description submodel.
3. The method for estimating the SOC of the battery pack of the electric vehicle according to claim 1, wherein: and B, performing correction operation on the average model of the battery pack in the step B through Kalman filtering and performing operation estimation based on an ampere-hour integration method.
4. The method for estimating SOC of a battery pack of an electric vehicle according to claim 3, wherein: the method also comprises the step of obtaining time delay through correction operation, and taking the time delay as an input parameter of the ampere-hour integration method.
5. The method for estimating the SOC of the battery pack of the electric vehicle according to claim 1, wherein: and C, analyzing the relevance of the battery pack capacity and DV and IC curves by referring to the principle of ICA and DVA methods, and representing the health state of the battery pack by using characteristic values and transformation coefficients of the DV and IC curves of the battery pack.
6. The estimation method of electric vehicle battery pack SOC according to any one of claims 1 to 5, characterized in that: step B is carried out under a Matlab/simscape platform.
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